score = eval(input("请输入有效成绩"))
if 60 <= score:
    print("成绩及格")
    if 90 <= score <=100 :
        print("成绩很好")


a = 30
if a > 20 :
    print("变量a大于15")
else:
    print("变量a不大于15")


score = eval(input("请输入成绩分数"))
if score >=60:
    print("成绩及格")
    if score >= 90:
        print("成绩很好")
    else:
        print("成绩一般")


score = eval(input("请输入成绩分数"))
if score >= 60 :
    print("成绩及格")
    if score >= 90 :
        print("成绩很好")
    else:
        print("成绩一般")
else:
    print("成绩不及格")
    if score < 30 :
        print("成绩极差")
    else:
        print("成绩较差")


score = eval(input("请输入一个成绩分数："))
if score >= 90:
    print("成绩优秀")
elif score >=80:
    print("成绩良好")
elif score >=70:
    print("成绩中等")
elif score >=60:
    print("成绩较好")
else:
    print("成绩不及格")

year = int(input("请输入年份:"))
if year %4 == 0 and (year %100 != 0 or year %400 ==0):
    print(year,"是闰年")
else:
    print(year,"不是闰年")
# 循环
a = 1
while a <= 100:
    print('今天是第%d天' % a)
    a = a + 1

n = 1
s = 0
while n <= 1000:
    s = s+n
    n = n+1
    #print(s) #序列状
print(s)  #直接出最后结果


for i in (5,6,7):
    print(i)



for i in range(1, 11):
    print(i , end=" ")
    print()
for i in range (1, 11 ,2):
    print(i , end=" ")
    print()
for i in range (2,11,2):
    print(i, end=" ")

i = 1
while i <= 5:
    print("上班星期为：",i)
    i = i+1
    t = 9
    while t <= 17:
        print("时间段：",t,end=" ")
        t = t+1
print(" ")


for i in range(1, 6):
    print("上班星期为：",i)
    for t in range(9, 18):
        print("时间段：", t , end="  ")
    print()
#
#
i = 1
while i < 10:
    j = 1
    while j <= i:
        print("%d*%d = %d" % (j, i, j*i), end=' ')
        j += 1
    print(" ")
    i += 1

i = 0
while i <= 5:
    i +=1
    print('星期为：',i)
    if i ==3:
        break

i = 1
while i <= 5:
    if i == 3:
        break
    print('星期为:',i)
    i +=1

for e in range(1,6):
    print('星期为:', e)
    if e == 3:
        break

for i in range(1,6):
    if i == 3:
        break
    print('星期为:',i )

i = 0
while i < 5:
    i = i + 1
    if i == 4:
        continue
    print('星期为', i)

for i in range(1, 6):
    if i == 4:
        continue
    print("星期为", i)

score = eval(input('请输入有效成绩'))
if score >= 60:
    print("成绩已及格")

score = eval(input('请输入成绩分数'))
if score < 60:
    print("成绩不及格")
if 60 <=score <80:
    print("成绩一般")
if 80 <= score <=90:
    print("成绩良好")
if 90 < score <= 100:
    print("成绩优秀")